1. Field of the Invention
The present invention relates to a method of controlling an optical storage medium, and more particularly, to an apparatus and a method of detecting sector sync signals on an optical storage medium.
2. Description of the Related Art
Optical storage media, such as a DVD-R or a DVD-RW, include land pre-pits (LPPs) which are formed by carving pits, where address information is contained on a land during a manufacture of a disk substrate. An LPP signal is read from an optical storage medium using a light beam, which is irradiated on the optical storage medium to follow tracks thereon, and is measured using an optical pickup of a data recorder before and after recording data on the optical storage medium.
A sequence of LPP data corresponds to 16 sectors physically having the same size as an error correction code (ECC) block to be recorded in a groove. Three bits b2, b1, and b0 are allotted to each sync frame of the LPP signal. A first bit (i.e., a first frame sync bit) among the three bits is placed at a specific region of a sync written in 8/16 modulated data in a groove. The three-bit arrangements are shown in Table 1 as follows.
b2b1b0Sector syncs at even positions111Sector syncs at odd positions110Data = 1b101Data = 0b100
The optical storage medium includes 16 sectors, and a sector sync signal indicating that a sector begins is recorded in each sector in the form of the three bits b2, b1, and b0 of the LPP signal. One sector can be divided into 26 frames, and the sector sync signal is recorded at an even position where a first frame begins or at an odd position where a second frame begins. The sector sync signal recorded at the even position has a binary value of “111”, and the sector sync signal recorded at the odd position has a binary value of “110”. Among the LPP signals, the LPP signals recorded on the optical storage medium having a binary value of “101” are interpreted as modulated signals of “1”, and the LPP signals recorded on the optical storage medium having a binary value of “100” are interpreted as modulated signals of “0”.
FIG. 1 is a diagram showing a relationship between the locations of the LPP signals and the sector on the optical storage medium. A one-bit LPP signal can be detected at the beginning of each frame. When one sector includes the 26 frames, each of the 26 frames is given a different number between 0 and 25. The sector sync signals, which include even syncs and odd syncs, can be respectively detected at the beginning of frames 0, 2, and 4 and at the beginning of frames 1, 3, and 5 begin. The LPP signal detected at the beginning of each frame has a one-bit size. The LPP signal is generally recorded at the beginning of an even frame rather than at the beginning of an odd frame. In a mastering process, the LPP signal located on a predetermined land is forced to move to an odd position on the same land if there already exists another LPP signal on a neighboring land, as shown in FIG. 2.
In order to record the data in the grooves on the optical storage medium or to reproduce the data recorded on the optical storage medium, precise position control is necessary on the optical storage medium. Accordingly, various strategies for detecting the sector sync signals, which can bring about less detection errors, are necessary to precisely perform such position control.